Finished Powders

Finished lots of powder are subjected to a series of tests designed to ensure performance in the various applications. The single most important application for copper powder is for self-lubricating bronze bearings. In the United States, these bearings are made predominantly from elemental blends of copper and tin. Since approximately 1960, preblended and lubricated mixtures of 90% Cu and 10% Sn that have graded dimensional change characteristics during sintering have increased in use.

Table 3 lists various grades of copper powders produced by the oxide reduction process; apart from bronze bearings, applications include copper-base friction materials, electrical contacts and brushes, diamond abrasive wheels, and copper additions to iron mixes for structural parts (Ref 1). Noncompacting applications include copper fillers in plastics, catalysts, and many chemical applications. The product brochures and data sheets of the powder producers generally provide details on the characteristics and performance properties of their powders (including sintered properties), as well as recommendations for specific uses.

Table 3 Typical properties of commercial grades of copper powders produced by oxide reduction

Chemical properties

Physical properties

Compacting properties at 165 MPa (12 tsi)(a)

Copper,

Hydrogen

Acid

Apparent

Hall

Sieve analysis, % Tyler

Density,

Strength(b),

%

loss, %

insoluble,

density,

flow,

+60

+100

+150

+200

+325

-

g/cm3

MPa

psi

%

g/cm3

s/50 g

325

99.8

0.13

0.06

2.91

26

0.4

39.7

46.6

13.3

99.8(c)

0.13

0.03

3.00

22

0.1

0.6

15.5

42.8

41.1

6.15

8.6

1240

99.8(c)

0.13

0.04

2.83

23

0.1

9.5

33.4

57.0

6.12

9.7

1400

99.8(c)

0.16

0.04

2.75

24

0.1

7.3

29.0

63.6

6.03

10.4

1500

99.7

0.18

0.06

2.51

0.5

7.0

92.6

6.04

99.7

0.21

0.06

2.31

1.2

98.5

99.6(d)

0.28

0.10

1.61

0.1

2.8

10.3

86.7

6.0

20.0

2900

99.6(d)

0.26

0.10

1.36

0.1

1.5

7.9

90.5

5.97

22.8

3300

99.5(d)

0.26

0.10

0.94

0.1

0.2

1.4

98.6

5.90

29.0

4200

(a) Measured with die wall lubricant only.

(b) Transverse rupture strength.

(c) For bronze self-lubricating bearings.

(d) For friction materials and electrical brushes

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